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Hopefully everyone has found Tokyo Dawn Records & Labs with their excellent plugin tools and a catalog of good contemporary music. They provide a few free plugins that work exceptionally well and they have advanced (GE) versions of these that add features and are very reasonably priced. The newest tool from TDR is Limiter 6 GE. In TDR parlance, GE is the Gentleman's Edition, the “non-free” version, and at this time Limiter 6 is available only in the GE edition, and as a free demo with limitations.

Limiter???

When asked to check out TDR's new plugin my first thought was, "a limiter? In 2017?" With the new standards for broadcast, streamed audio, and even portable music players mandating ‘average’ program levels rather than peak levels, the idea of a limiter seems almost archaic.

In short, Limiter 6 GE is a limiter like a Lamborghini Huracan Spyder is a 'car'! Yes, Limiter 6 has a good old peak limiter function, but it has a lot more. There is a compressor module, the peak limiter, a clipper module, a high frequency limiter, an output protection limiter, and some very 2017-appropriate metering, including true peak and EBU compliant loudness meters. Each module has a plethora of features and adjustments, and it costs a lot less than the Lamborghini!

In Use

The Limiter 6 GE manual includes excellent descriptions of each module and their appropriate applications, and suggests trying each individually to get a feel for how they affect levels and audio quality. This is an excellent idea. Of the six total modules (and thus, the product name) the four dynamics modules are movable in order of the audio path so that the compressor may precede the clipper, or you may have the clipper precede the compressor, and so forth. And you may turn off and hide any module since for most work you won't need all of them. The only modules not movable are the output module (which also provides a final protection limiter) and the metering section, which are always the last two in the audio chain.

If I had to choose just one overall feature of Limiter 6, it would be it's ability to process not only mono and stereo, but also dual-mono (Peak Limiter & Compressor) and mid-sides audio (all processors). If you haven't yet used mid-sides processing, look it up on the web. It's especially effective on full mixes and sub-mixes, but can yield some very useful results on any stereo audio stream. But picking only one 'special' feature isn't fair - there are many powerful choices of compression and limiting control modes, "hidden" multi-band processing, two parallel processing modes, the "Delta" mode, the equal loudness bypass mode, and the earlier mentioned EBU compliant metering.

How Does It Work?

In short, very well! I tried each module separately as the manual suggests, and each is excellent in its own right. Some controls will be familiar, but others have 'odd' names and control the dynamics differently than other dynamics processors. Along with Ratio, Threshold, Attack, and Release you will find Focus, Separation, and Recovery controls.

The Focus control in the Peak Limiter enables adjusting how the gain reduction responds to frequency, with positive settings reacting more to mid frequency transients and negative values favoring low & high bands.

The Separation knob found in the Clipper module adjusts how the clipper reacts to peaks in different frequency bands, similar, but not identical to the Focus function.

Recovery is found in the Peak Limiter, but is not a traditional release function since it only partially affects the envelope of the level return after gain reduction.

The Delta mode mentioned earlier is found in the Output Module and provides a fascinating feature that lets you hear the difference between the original music and the overall processed form, basically, what has been removed. With light processing this may yield very quiet spurious sounds, and with some heavy limiting and compression you may hear a rather full musical production! You might even use this mode to create some unique ‘beats’!

Layout

Limiter 6 appears as a ‘rack’ with up to 6 modules. At the top left is a window to choose presets and an A/B comparison switch, while over to the right is a Module button that lets you add or remove any module, a Stereo/Mono control, processing quality button, a Help button, Settings and Info/About button.

The quality mode is of special interest since it affects how much CPU resource is required. There are four modes, Precise (the normal setting), Eco (economical of course), Insane (maximum quality), and Low Latency. My tests (on a 3.5 GHz quad core i7 PC with 16 GB RAM) found that with all six modules active, Precise mode required about 1.8% of CPU resources (varies a bit with actual settings and music material), Eco reduced that to about 1%, Insane drove it up to about 4%, and Low Latency somehow reduced the CPU load to around 0.5 % while at the same time reducing latency to a mere 12 samples (0.27 msec at 44.1 kHz)! All modes other than Low Latency have a latency of 460 samples (10.4 msec at a 44.1 kHz sample rate). Since the low latency performance seemed to defy logic, I looked into it more and found that it deactivates some functions such as the final output limiter, true peak monitoring, and likely some others. However, I’d expect most engineers will use Limiter 6 in a mastering or mixing environment rather than during tracking, so for those uses latency is pretty much a ‘don’t-care’ issue.

At the top of each module are VU style gain reduction meters whose scale can be changed by clicking the upper or lower half of the meter, using the mouse wheel, or right-clicking to open a menu. Note that these meters will display dual needles for some modes such as mid-sides processing, which is very effective.

Next to the meters of the compressor, clipper and peak limiter are Drive knobs that control the input level into the respective module. The High Frequency Limiter does not have a Drive knob, but has a Threshold control and the ability to respond to absolute levels or relative levels.

Note there are no output level controls, so if some modules are reducing gain too much, you may need to pump up some drive levels along the way.

Modules

The compressor is similar to many compressor models, and responds to all but the fastest peaks. It has the usual compressor controls and also provides three gain control modes, Alpha (a clean conventional gain control), Sigma (a nonlinear mode where timing and gain reduction interact, much like the ‘colorful’ Molot compressor), and Leveler (gain only changes when the signal level crosses an upper or lower threshold). I found these various gain control modes to produce rather different results with most tracks/mixes I tried.

The peak limiter is a lookahead “brick wall” limiter that can stop almost any overshoot above the threshold setting. It includes a very sophisticated multiband control mode and a wideband mode. And its “brick wall” action can be turned off to allow brief ‘spikes’ to pass on to subsequent modules if desired. As described above, the Focus control further modifies how the peak limiter responds to sounds across the audio spectrum. It’s certainly not your father’s peak limiter!

The high frequency (HF) limiter module is designed to control the upper few octaves of the audio spectrum, basically above a few kHz. As mentioned earlier, this module can be set to respond to absolute or relative levels providing flexibility in how it tames the upper registers. I found it great to reduce the harshness of some variable sounds like cymbal crashes, where a light hit can still maintain ‘air’ while the harmonics of a hard hit can be softened to a bearable level.

The Clipper module is intended to ‘chop’ off instantaneous, short term peaks, but you can also use it to destroy slower waveforms if you need a lot of distortion! It has three detection modes with a “Brick Wall” mode being the default. There is also an “Open” mode that smooths the clipping effect significantly, and an “LF” mode for control of bass sounds that will leave higher frequencies alone. In addition, as with the other modules, you can process stereo, mono, dual-mono, and mid-sides. Clipping, used properly, can really shave off ‘out-of-control’ spikes in music without causing any ‘pumping’ or ‘breathing’ effects. To be honest, I have a few clipper plugins that I rarely use due to the harsh results - this clipper is a whole different beast, especially in Open mode.

Note that every dynamics module has parallel processing capability via a “Dry” control in the lower right corner. Double-click the DRY AMT label and it changes to DRY MIX, and vice versa. The Mix mode adds a portion of the incoming signal to the processed signal (shown as dB) and will increase the volume level as the Mix approaches 0 dB, while the Amount mode cross-fades the incoming dry signal with the processed signal (shown as a percentage) and maintains the same volume. Very cool!

The Output module includes a Drive control, a built-in final limiter, Auto Pad, Bypass and the Delta controls. It is always the last processing module in the Limiter 6 ‘rack’. It cannot be turned off, however, you can turn off the True Peak/PCM ceiling buttons and even shut down the limiter should you wish to use an external limiting module. With either the True Peak or PCM button on, turning up the Drive level will only push the signal harder against the output limiter ceiling. The ceiling level can be set in the window below the True Peak/PCM selection buttons, and a separate value can be entered for each mode. If using True Peak you may still want some headroom (a dB maybe), but when using PCM you should dial in an additional couple dB to guard against aliasing when data compression encoding schemes are applied in broadcast/streaming systems.

The metering section provides a number of readout options and has all I’d need except a dynamic range readout. However, this is easy to calculate (True Peak minus the EBU R128 Integrated program loudness value). As I mentioned at the start of this review, with the move in broadcasting, streaming and even portable players toward ‘average’ levels from the last couple decades of using peak limits, there is no advantage to compressing dynamic range down to a couple dB and raising the level as high as possible since it will be delivered with its average program level set down 10, 12, 15 dB or more depending on the delivery platform!

Conclusions

TDR Limiter 6 is an amazing rack of dynamics controllers and measurement tools at a price one could pay for a single processor. It provides extreme flexibility for taming peaks and loudness variation in any musical style. Although Limiter 6 may be seen as being aimed at mastering or mix bus use, modules can be turned off and hidden, greatly reducing CPU loads, and I found it very useful for individual tracks during mixing and even tracking, especially the HF Limiter and Clipper which perform far better than any other such plugins I have. Tracking in Low Latency mode requires very little CPU resource and yields only 0.27 msec of latency!

Since it has no external side-chain input, Limiter 6 cannot be used for ducking purposes, but there are a lot of tools out there if you need to duck.

All in all, another excellent set of tools from Tokyo Dawn Records and Labs!

Pros:

Low CPU use in Eco mode and Low Latency mode even with all six modules engaged.

Low Latency mode provides only 12 samples of latency at 44.1 kHz, a mere 0.27 milliseconds, fully usable for tracking,and it does not use significant CPU resources, but does defeat a few processes.

EBU metering and true peak measures match my ‘gold’ standard, allowing you to set appropriate program loudness levels and enabling estimation of PLR (Peak-to-Loudness Ratio), the current term for dynamic range.